In the technical field of refrigerators, valve devices are known, which are used to control a cold air flow, so as to allow the temperature in the refrigeration chamber or cell to be controlled.
A device of this type, which is also known as a damper, generally operates by controlling a plug, which selectively frees and obstructs a passage, which is meant for a cold air flow to get through, the cold air flowing by being suited to perform a heat exchange in the refrigeration chamber or cell. Typically, the above-mentioned heat exchange takes place by temporarily allowing the cold air coming from the freezing chamber or cell of the refrigerator, which has a lower temperature (in general, equal to a value ranging from approximately −18° C. to approximately −20° C.), to flow to the refrigeration chamber or cell, which has a higher temperature (in general, equal to a value ranging from approximately 0° C. to approximately −4° C.)
Hence, by freeing and obstructing the passage according to predetermined criteria, for example with a thermostatic kind of control, the device is able to permit the adjustment of the total quantity of cold air flowing through the passage in order to reach the refrigeration chamber or cell, so that it can assume the temperature value desired, which can typically be selected by the user.
In the technical field, valve devices of the type described above are known, which use electric motors of the stepper type or low-power synchronous motors, which are connected to the plug, so as to move it between the opening position and the closing position.
This technical solution, though, has many drawbacks, among which there is the high noise mainly due to the “jerk” operation that characterizes the electric motor of the stepper type, which tends to produce vibrations that can normally be perceived in a significant manner, in particular in slow running mode.
In the art are known some devices as described in their respective documents.
For instance, DE 10316209 A1 discloses a damper that consists of a fixed frame with guides in which a moving element slides. The degree to which the slots coincide controls the air flow. Two form memory wires of e.g. nickel-titanium alloy are each fixed at one end to the frame and at the other end to the moving element. These wires contract when heated by an electric current and alter the position of the moving element to control the air flow.
According to US 2008/257086 A1, a driving force transmission mechanism in a motor type damper device, when a small AC synchronous motor rotates in one direction and a tooth-missing gear part of a tooth-missing gear engages with the first rack part of a rack member the rack member is moved upward to operate a baffle in an open direction and, when the tooth-missing gear part engages with the second rack part of the rack member, the rack member is moved downward to operate the baffle in a close direction. In this manner, even when the baffle and the rack member are operated in both directions, the tooth-missing gear is required to be rotated in only one direction and the rotation of the small AC synchronous motor is not required to be reversed. Therefore, the structure of a control circuit for the motor type damper device can be simplified.
U.S. Pat. No. 5,816,061 A discloses an apparatus and method for controlling the temperature in a refrigerating chamber of a refrigerator by supplying appropriate cooled air to each of the compartments of the refrigerating chamber according to a temperature in each of the compartments. A cooled air controlling plate is provided for controlling the size of the cooled air discharge outlet according to the individual temperatures in the compartments. The cooled air controlling plate is moved in an up and down direction in multiple stages depending on the temperature in the refrigerating chamber to control the cooled air discharge rate to each of the compartments of the refrigerating chamber so as to make the temperature in the refrigerating chamber uniform.
According to EP 0905461 A2, cool air is fed into a compartment of a refrigerator through a plurality of apertures. The air flow is directed up and down by pivotable blades associated with respective apertures. The apertures can be blocked by pivoting the blades to the maximum extent.